This invention relates generally to the field of position tracking systems and video-imaging systems, and more specifically a method and apparatus for accurately detecting from a remote distance the location and orientation of a moving person or vehicle in order to make corresponding changes of images displayed on a viewing screen.
There are various prior art patents and devices which relate to simple, one-purpose detection systems. However, the extent of movement monitored is very limited and the techniques relatively crude and/or complicated. Typical examples of such prior art devices are U.S. Pat. No. 3,678,283 issued July 18, 1972 for Radiation Sensitive Optical Tracker, U.S. Pat. No. 4,124,838 issued Nov. 7, 1978 for Apparatus For Position Determination, U.S. Pat. No. 3,745,519 issued July 10, 1973 for Small Craft Positioning System, U.S. Pat. No. 3,869,694 issued Mar. 4, 1975 for Ultrasonic Control Apparatus For An Oculometer, and U.S. Pat. No. 3,670,097 issued June 13, 1972 for Stereoscopic Television System and Apparatus.
However, none of the aforementioned prior art devices provide the simplicity and precision required for monitoring a mobile unit and/or an individual person which move through a device implementation space and change their lateral and vertical placement as well as their line-of-sight orientation. More specifically, even though the technology exists for visually displaying a three dimensional environment on a screen, there has been no known technique or apparatus developed for allowing a person to move through a simulated environment while simultaneously observing through a viewing screen the resulting image changes in size, vantage point, and depth perception based on the location and rotational orientation along the line-of-sight of the viewer as if the viewer were actually moving through such an environment.
Accordingly, it is an object of the present invention to overcome the deficiencies of the limited prior art techniques for position tracking, and to provide an improved and reliable method and apparatus for placing a person in a simulated environment and allowing him to experience the visual consequences of moving about in such environment without having to physically construct the components of the environment and without having to place a person physically therein.
It is an object of the present invention to provide a method and apparatus which enables a viewer to see and experience the visual impressions of walking around a pre-determined environment without actually being present in that environment. A related object is to provide a viewing screen connected directly to video information and video data storage in a computer memory so that an updated representation of the simulated environment will appear on the screen based on the position with respect to a fixed coordinate system, the direction of the line-of-sight of the viewer, and an associated rotation about this line-of-sight.
Another object is to provide an invention of the aforesaid characteristics which has implements a simple method of identifying the position of the viewer many times during each second so that the corresponding changes on the display screen can also be made many times during each second to provide a motion picture with movements which occur smoothly as viewed by the naked eye, with minimal lag time between movement and its related image change.
A further object is to use a one-way sonic signal which travels directly between a sonic transmitter and a sonic receiver, and to provide a time measuring system to accurately determine the precise time elapsed between the departure of the sonic signal from the transmitter and the arrival of the sonic signal at the receiver. A related object is to provide a sufficiently high frequency electromagnetic (EM) pulse such as a UHF or infrared (IR) signal which commences traveling at the same instant as the sonic signal, thereby providing a precise indicator of the departure time of the signal.
Another object of the present invention is to provide a method of differentiating between ultrasonic signals generated from transmitters physically separated from each other so that a receiver can identify the source of each ultrasonic signal which is received. A related object is to provide a method of generating ultrasonic signals in a predetermined timing sequence, thereby eliminating any need for sensing the direction travelled by the signal and also eliminating the need for encoding the signal with an origin identification.
A further object of the invention is to determine the relative change of a mobile unit's position remotely without having to visually observe the change, thereby making it possible to continually monitor the position of a mobile unit in a device implementation space without having any physical contact with the mobile unit and independently of whether the implementation space is in darkness or low visibility lighting conditions.
Still another object of the invention is to be able to monitor the movement of a plurality of mobile units in a device implementation space without having to send a separate set of ultrasonic signals with respect to each individual mobile unit. A related object is to fixedly mount an array of transmitters above a device implementation area and to locate receivers on the top portion of each mobile unit in order to achieve a direct signal path from the transmitters to the receivers independent of their location within the implementation space.
Yet another object of the invention is to simplify the calculations required to determine the change of a mobile unit's position by mounting an emitter array of ultrasonic transmitters so that they remain in the same relative fixed position between themselves even though the array may move as a unit. A related object is to mount a detector array of ultrasonic receivers so that they remain in the same relative fixed position between themselves even though the array may move as a unit. Another related object is to allow the mobile unit to move through angular displacement as well as to move through a translational displacement.
Still a further object is to provide a single detector for receiving ultrasonic signals from each of the different ultrasonic transmitters. A related object is to provide circuitry connected with each receiver for determining the time of travel of each ultrasonic signal from its transmitter to the receiver.
A further object is to provide a viewing screen which displays one image for the right eye and another image for the left eye in order to achieve realistic stereoscopic display of the simulated environment.
Another object is to provide three separate ultrasonic transmitters which send signals to three separate ultrasonic receivers, and to provide digital circuitry associated with each of the receivers to measure the time taken for the signal to travel from each of the transmitters to the receiver. A related object is to provide a method of processing the time measurement data in order to determine the changed location and alignment of a mobile unit which carries either the three transmitters or alternatively the three receivers.
Another object is to provide flexibility so that the simulated world does not have to be in its true size relative to the viewer's size, but could include a scaled down version as might be used when teaching relative views encountered while traveling through the solar system, or alternatively a scaled up version such as would be encountered by a viewer walking through and around the molecular structure of various compounds.
A further object is to provide means for allowing a viewer to interact with the simulated visual environment by directing a pointer toward a specific thing as viewed on the screen, or by reaching for and/or touching a specific thing as viewed on the screen.
Another object is to provide a method of visually moving through a simulated environment by operating a manual control which allows the viewer to remain stationary in the device implementation space while changing the position and/or orientation in the simulated environment.
These and other objects of the invention will become evident to those skilled in the art based on the exemplary embodiments of the invention shown in the attached drawings and described in detail hereinafter.